Welcome to your go-to Java String Manipulation cheatsheet. Below you’ll find the most commonly used String methods in Java, complete with examples to help you write clean, efficient code and boost your blog’s search visibility.

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Inspection & Info

Method	Description
int length()	Returns number of characters
boolean isEmpty()	Returns true if length == 0

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Character Access & Code Points

Method	Description
char charAt(int index)	Character at given index
int codePointAt(int index)	Unicode code point at index
int codePointCount(int beginIndex, int endIndex)	Number of Unicode code points in range
int offsetByCodePoints(int index, int codePointOffset)	Index shift by code points

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Comparison & Matching

Method	Description
boolean equals(Object other)	Case-sensitive equality
boolean equalsIgnoreCase(String other)	Case-insensitive equality
int compareTo(String another)	Lexicographical compare
boolean matches(String regex)	Full-match regex
boolean regionMatches(boolean ignoreCase, int toffset, String other, int ooffset, int len)	Region comparison

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Searching

Method	Description
boolean contains(CharSequence s)	Checks if substring exists
int indexOf(String str)	First occurrence of substring
int lastIndexOf(String str)	Last occurrence of substring
boolean startsWith(String prefix)	Checks prefix
boolean endsWith(String suffix)	Checks suffix

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Extraction & Substrings

Method	Description
String substring(int beginIndex)	From beginIndex to end
String substring(int beginIndex, int endIndex)	Between begin (inclusive) and end (exclusive)
CharSequence subSequence(int start, int end)	Returns same as substring as a CharSequence

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Case Conversion & Trimming

Method	Description
String toLowerCase()	All chars to lower case
String toUpperCase()	All chars to upper case
String trim()	Remove leading/trailing whitespace
String strip() (Java 11+)	Unicode-aware trim

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Replacement & Modification

Method	Description
String concat(String str)	Append given string
String replace(char oldChar, char newChar)	Replace all occurrences of one char
String replaceAll(String regex, String replacement)	Replace via regex
String replaceFirst(String regex, String replacement)	Replace first match via regex
String repeat(int count) (Java 11+)	Repeat this string

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Splitting & Lines

Method	Description
String[] split(String regex)	Split by regex
String[] split(String regex, int limit)	Split with max parts
Stream<String> lines() (Java 11+)	Stream over lines

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Conversion & Encoding

Method	Description
char[] toCharArray()	Chars → array
byte[] getBytes()	Default-charset bytes
String intern()	Canonical representation from pool

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Streaming (Java 8+)

Method	Description
IntStream chars()	Stream of UTF-16 code units
IntStream codePoints()	Stream of Unicode code points

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Formatting & Joining

Method	Description
static String format(String fmt, Object… args)	printf-style formatting
String formatted(Object… args) (Java 15+)	Instance formatting
static String join(CharSequence delim, CharSequence… elems)	Join with delimiter

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Static Utilities

Method	Description
static String valueOf(Object obj)	Any value → String
static String copyValueOf(char[] data)	char[] → String

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Usage tip: Strings are immutable—most methods return a new String, so you can chain calls:

String s = original.trim()
                   .toLowerCase()
                   .replace("foo", "bar")
                   .substring(0, 10);